1. Field of the Invention
The present invention relates to engine measuring equipment.
2. Related Background Art
Conventionally, in order to assess whether a developed or manufactured engine is provided with the predetermined performance, engine bench tests are implemented in which an engine to be tested is mounted on a bench (an engine bench), the engine output shaft is brought into connection, through a torque meter as well as a rotation counter, with a dynamometer, which is operated to measure and assess the performance of a stand-alone engine.
For such engine bench tests, various techniques have been researched and developed. For example, Japanese Patent Application Laid-Open No. 02-196942 discloses a testing device for engines which aims to improve responsiveness and controlling accuracy for an automatic revolving speed control (ASR) system and automatic load control (ATR) system by suppressing a change of revolving speed by detecting the change of load by the ASR system. Japanese Patent Application Laid-Open No.02-226036 discloses a controlling apparatus for engine testing technique which aims to achieve control of a high-speed response with high accuracy by detecting the running condition of an engine, operating a controlling constant of an engine controlling part in accordance with the running condition and outputting said controlling constant to the engine controlling part. Japanese Patent Application Laid-Open No.03-075539 discloses an engine testing apparatus which aims to enhance the efficiency of the test of an engine and to make it possible to realize highly accurate engine test by providing means for computing the changing coefficient of engine torque, means for computing the correcting amount of opening degree and means for correcting the opening degree. Japanese Patent Application Laid-Open No.2002-082020 discloses an engine torque estimating device of engine bench system which aims solve a problem that when an engine torque map is used in an engine bench system, an error of an engine torque estimated value affects a torque command value of a dynamo meter to disturb accurate engine benching. Japanese Patent Application Laid-Open No.2004-177259 discloses a controller for engine tester which aims to solve a problem in an engine tester for simulating a load by using a controller having a vehicle model part and a torque control part, that an unstable phenomenon appears in engine speed when a response is slow in a closed loop of a shaft torque control system relative to a closed loop of the model part.
Engine bench tests which are regarded most important for the engine performance assessment are to measure the relationship between the engine torque Te and the revolution N. However, engine bench tests provide torque measured with a torque meter (hereinafter referred to as shaft torque Td) which is different from engine torque Te as an output parameter representing pure engine performance, and therefore, from the shaft torque Td measurable with engine bench tests, the engine torque Te necessary for assessing the original performance of an engine need to be obtained.
Engine torque Te and shaft torque Td are corelated under Te=Td−I×dN/dt (I: moment of inertia of a rotating shaft including an engine, the transmission system from the engine to a dynamometer and the dynamometer). Therefore, conventional engine test equipment measured the shaft torque Td, which used to be regarded as engine torque Te, under a state with the revolution N made constant as described in Japanese Patent Application Laid-Open No. 2000-321175, that is, the state with dN/dt approximated to 0. Incidentally, a test method of measuring torque under a state with the revolution N made static (a steady state) like this is generally called a steady-state test.
However, such engine test equipment had technical problems described as follows.
The engine test equipment disclosed in Japanese Patent Application Laid-Open No. 2000-321175 needs to vary opening degrees of the throttle bulb under a state with revolution N made constant as described above, and, however, not only the revolution N but also most physical phenomena, generally make transition to a static state via a transient state (a state with values not stabilized at a constant value so as to repeat swinging). Accordingly, it take as much as several tens of seconds for the revolution N to get settled to a static state, and eventually it used to take a period of several days to obtain the revolution as well as the torque data for each opening degree required for engine performance assessments.
Moreover, since items required for the holistic assessment of engine performance is not limited hereto, but hundreds of items complete a test, measurement data are desirably to be obtained as much as possible even for a single item.
The present invention has been completed in view of such conventional problems, and it is an objective to provide engine measuring equipment for obtaining engine torque Te regarded as necessary for engine performance assessments for a short time period during a period when the revolution N is under a transient state, without depending on a conventional steady-state test method.